Ensenada Center for Scientific Research and Higher Education

About: Ensenada Center for Scientific Research and Higher Education is a facility organization based out in Ensenada, Mexico. It is known for research contribution in the topics: Population & Nonlinear system. The organization has 1934 authors who have published 3733 publications receiving 63115 citations.

White light generation and anisotropic damage in gold films near percolation threshold

Abstract: Strongly enhanced and confined electromagnetic fields generated in metal nanostructures upon illumination are exploited in many emerging technologies by either fabricating sophisticated nanostructures or synthesizing colloid nanoparticles. Here we study effects driven by field enhancement in vanishingly small gaps between gold islands in thin films near the electrically determined percolation threshold. Optical explorations using two-photon luminescence (TPL) and near-field microscopies reveals super-cubic TPL power dependencies with white-light spectra, establishing unequivocally that the strongest TPL signals are generated with close to the percolation threshold films, and occurrence of extremely confined (~ 30 nm)and strongly enhanced (~ 100 times) fields at the illumination wavelength. For linearly polarized and sufficiently powerful light, we observe pronounced optical damage with TPL images being sensitive to both wavelength and polarization of illuminating light. We relate these effects to thermally induced morphological changes observed with scanning electron microscopy images. Fascinating physics involved in light interaction with near-percolation metal films along with their straightforward and scalable one-step fabrication procedure promises a wide range of fascinating developments and technological applications within diverse areas of modern nanotechnology, from bio-molecule optical sensing to ultra-dense optical data storage.

Screening of anthocyanins in single red grapes using a non-destructive method based on the near infrared hyperspectral technology and chemometrics.

Abstract: BACKGROUND Anthocyanins are the main compounds responsible for the colour of red wines and therefore it may be important to evaluate the content of the aforesaid secondary metabolites during grape ripening due to the crucial importance to determine wine colour. Nowadays, there is a growing demand of rapid and non-destructive analytical tools for analysing grapes, such as the emerging hyperspectral analysis. RESULTS The hyperspectral images of intact grapes (Vitis vinifera L. cv. Tempranillo, Graciano, Garnacha and Mazuelo red grape from vineyards located in the D.O.Ca. Rioja at two different developmental stages) were recorded using a near infrared hyperspectral imaging device (900–1700 nm). Reference values of anthocyanins were obtained by HPLC-DAD. Calibrations were performed by modified partial least squares regression and present a good potential (coefficient of determination of 0.72 and standard error of cross-validation values of 0.78 and 0.70 mg per grape for total and non-acylated anthocyanins respectively). CONCLUSION The procedure reported here presents a good potential for a fast and reasonably inexpensive screening of these compounds in intact single berries. Moreover, the heterogeneity of anthocyanins within the same ripeness stage could be evaluated using this non-detructive tool. © 2015 Society of Chemical Industry